By Xanthe Gregory, ABC NewsA driver is unaccounted for and up to seven semi-trailers have been destroyed by fire after trucks crashed into a rest area near Goulburn in Australia's New South Wales."It appears two trucks collided and careered into five other rigs at a roadside rest stop," Fire and Rescue NSW said in a statement.Emergency services received calls just after 5am that multiple trucks were alight on the Hume Highway at Breadalbane, 30 kilometres south-west of Goulburn.NSW Ambulance says six people were treated at the scene for minor injuries, while one person remains unaccounted for.There are reports of explosions, with a 300-metre exclusion zone in place."One truck was carrying eight tonnes of butane cans, another was transporting resin, a third contained memory foam and a fourth was packed with alcohol, fuelling the resulting fire and explosions," FRNSW said in a statement.The Hume Highway is closed in both directions between Gunning and Cullerin Road in Breadalbane.Motorists are being urged to avoid the area and allow more than an hour for extra travel time on diversions through Canberra via the Federal and Barton Highways.More than 30 firefighters are on the scene working to contain the blaze and monitor hazardous material runoff.Multiple RFS water tankers and ambulance crews are assisting.- ABC